An era of “transceiver bloat” is beginning. Information systems like the World-Wide Web, Bluetooth and IEEE802.11b networks, cellular and satellite communications, and IRDA communications ports are part of the increasingly sophisticated, wireless information network that we use to exchange information. The impact of this communication web is pervasive in our lives, but the expense of installing and maintaining the transmitters and receivers in a transceiver network remains significant. This expense is especially apparent where the economies of mass production fail. Cellular coverage becomes spotty in thinly populated areas. The cost of maintaining a satellite constellation can limit the availability of the global positioning system at different geographic locations and times. Signals from GPS are difficult or impossible to acquire indoors, and often require additional or modified electronics to function at all in a building. Assistive technologies like captioning systems for the hard-of-hearing or even Braille signs for the blind must be mandated in many commercial environments by law, e.g., the Americans' with Disabilities Act.
When economies of scale do apply, we tolerate the intrusive and often expensive installation and maintenance of transmitters, e.g., Bluetooth transmitters, cellular phone towers, and wired data ports, on the promise that the connectivity provided by these systems justifies their addition. Furthermore, adding additional features to a network, e.g., position locating in a communication network, may bring additional technical and economic complications.
The present invention relates to a communication network based on frequency-modulated radiation. Among other possibilities, it enables existing lighting systems to be used to transmit the signal. Because this system can take advantage of existing installed light fixtures, uses little or no extra power, and can operate with little or no extra wiring, it provides desirable communications capabilities without the “bloat,” i.e., without special installation efforts beyond normal maintenance or installation activities for lighting products, for example. In one embodiment, the invention is “dual-use,” preserving one feature, e.g., illumination, while adding another, e.g., communication. Both functions, communication and illumination (and potentially other functions) are preserved, available at all times in principle without interfering with each other. The invention as applied to lighting eliminates undesirable visual flicker and other distracting optical phenomena in the system and so allows continuous use of the lighting fixtures as lighting while also providing the medium for communication. It allows analog, digital or analog/digital data to be sent and received. It increases the bandwidth available to transmit data, and it enables a number of applications to be performed using the system. Improvements made in the current invention could result in unprecedented performance advantages in the operation and implementation of lamp transceiver systems.